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This paper presents a method to obtain improved foam/pillar structural designs to help enhance occupant interior impact protection. Energy absorbing foams are used in this study with their thickness and crush strength being selected as primary design variables for optimization. The response surface techniques in the design of experiment are used in the optimization process. Head impact analyses are conducted by a CAE model with explicit, nonlinear, dynamic finite element code LS-DYNA3D. A baseline model is developed and verified by comparing the simulation results with the experimental data. Based on this model, the anticipated effects of stiffness of the pillar structure and the trim on the Head Injury Criterion (HIC) results are also assessed. The optimization approach in this study provides a comprehensive consideration of the factors which affect the HIC value.

Head Impact Criterion (HIC) numbers obtained from interior head impact testing with the NHTSA-designed Free Motion Headform (FMH) are influenced by many variables. The high level of variability experienced in the NHTSA-proposed Interior Head Impact Test presents a challenge to today's automotive engineers. Primary contributors to HIC variability include (1) impact speed, (2) headform calibration performance, (3) design/build part variation, and (4) target point impact accuracy. This study shows that controlling these variables during testing can improve test data repeatability and reproducibility, as well as reduce design and testing time.

This paper describes the development of a three-dimensional lumped-mass structure and dummy model to study barrier-to-car side impacts. The test procedures utilized to develop model input data are also described. The model results are compared to crash test results from a series of six barrier-to-car crash tests. Sensitivity analysis using the validated model show the necessity to account for dynamic structural rate effects when using quasi-statically measured vehicle crush data.